SRM 621 D2L3: MixingColors, math

 

 

Calculate the basis of the linear space by using Gaussian deyuan, that is, the rank of the matrix.

Code:

 

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                      using namespace std;#define CHECKTIME() printf(%.2lf, (double)clock() / CLOCKS_PER_SEC)typedef pair
                      
                        pii;typedef long long llong;typedef pair
                       
                         pll;#define mkp make_pair#define FOREACH(it, X) for(__typeof((X).begin()) it = (X).begin(); it != (X).end(); ++it)/*************** Program Begin **********************/class MixingColors {public:int minColors(vector 
                        
                          colors) {int res = 0;int n = colors.size();bool used[55];memset(used, 0, sizeof(used));for (int i = 31; i >= 0; i--) {int pivot = 0;for (int j = 0; j < n; j++) {if (used[j]) {continue;}if ((colors[j] >> i) & 0x1) {if (!pivot) {pivot = colors[j];used[j] = true;++res;} else {colors[j] ^= pivot;}}}}return res;}};/************** Program End ************************/